Grief over Malaysia Airlines Flight 17, support for those left behind

(CNN) -- As officials search for answers into the downing of Malaysia Airlines Flight 17, details are emerging about the 298 passengers and crew aboard the plane. Families, friends and mourners from around the world united on social media to express their horror and sadness over the disaster.

A Facebook page for flight attendants worldwide became a forum for grieving members of the flying community. A status update from the site administrator asked, "For those of us flying today, did you find it hard to put your uniform on and greet your passengers? I know I do." One comment below it urged, "Non crew readers (like myself): give your cabin crew a smile today."

Among the dead were a number of AIDS experts, including researcher Joep Lange, former president of the International AIDS Society. They were on their way to the International AIDS Conference in Melbourne, Australia.

"Joep Lange was a towering presence in the fight against AIDS since the beginning of the epidemic and a wonderful friend, colleague, and teacher," said amfAR CEO Kevin Robert Frost in a statement. "He inspired legions of AIDS researchers, healthcare workers and activists and was an inspiration to me personally. He will be sorely missed."

UNAIDS Executive Director Michel Sidibe said he hoped the AIDS research community's work could be furthered as a way to come out of this tragedy. "We should use this moment of sadness as a moment for us to push our agenda," he said, "our agenda for saving lives of millions of people."

#AIDS2014 was trending on social media, with individuals and nonprofits tweeting their support. Some expressed concern about the impact of years of lost knowledge with those who perished on the flight.

The UK based charity Kidasha confirmed on their website that they've received a surge in donations from people wishing to pay tribute to MH17 victim Richard Mayne. Mayne had trekked to Everest base camp earlier this year to raise money for the charity, and supporters took to social media to urge others to donate in his honor.

Other messages offering support poured in from around the world.

"It has been 18 years since I lost my fiancé in TWA Flight 800, yet with every new air crash, I, along with all the other families who experienced loss that day, revisit those emotions and are brought back to Day One," said Heidi Snow, referring to the plane that exploded over the shores of Long Island, New York, in 1996.

Snow is founder of ACCESS, an organization that provides support to those who have lost friends or family in air disasters.

"We want all those who are suffering from loss after this air disaster and any other disaster to know we are here, we understand, we care, and we can help you," she said.

ACCESS has a toll-free help line -- 877-227-6435 -- and a website where people can reach out to survivors from past air disasters, or get support from others who have lost people in air tragedies.